Here are the first plastic circulating coins in the world, those from Transnistria (secessionist region of Moldova, de facto Russian protectorate). As you can see they have a kind of serial number: these are the "AA series".

"Awaken, my child, and embrace the glory that is your birthright!
Know that I am the Overmind, the eternal will of the swarm,
and that you have been created to serve me."